Droplet transfer behaviour in twin-body plasma arc welding

Abstract

A novel process, named twin-body plasma arc welding (PAW), is proposed in this study. In this novel process, the wire is used as introduced electrode to adjusting the energy distribution between base metal and droplet, and a strong plasma flow force is applied to the droplets. To understand the characteristics of droplet transfer behaviour in this process, this paper analyses the changes in the forces acting on the droplet and carry on experiments to study the effect of the current separation ratio and plasma gas flow rate on droplet transfer behaviour. The results show that as the current separation ratio increases, the total energy acting on the droplet and the promoting force of droplet transition are enhanced, and the droplet transfer behaviour and wire melting speed are changed significantly. As the plasma gas flow rate increases, the plasma flow force is enhanced, and the droplet transfer behaviour is changed, but the droplet transfer position is almost unchanged. Through reasonable parameter matching, the spray transfer could be realized under low current, and the droplet transfer mode could be freely changed from globular to spray when the total current remains unchanged.